1. Field of the Invention
The present invention relates to an optical element having an optical functional layer obtained by polymerization of a polymerizable liquid crystal material, wherein the above-mentioned optical functional layer has a high hardness.
2. Description of the Related Art
Conventionally, an optical element such as a retardation film and a circularly polarized light control optical element, used for an image display apparatus or the like, can be used in a state assembled in an image display apparatus such as a liquid crystal display apparatus. In production of such an image display apparatus, another member can be provided by superimposing on the above-mentioned optical element. For example, in the case the optical element is a retardation film used for a liquid crystal display apparatus, or the like, a spacer (column) is formed on the retardation film for making the liquid crystal layer gap even.
At the time, in the case the hardness of the optical element itself is low, the optical element may be distorted at the time of forming the above-mentioned spacer, or the like so that the accuracy as the optical device cannot be maintained. Moreover, in the case the optical element itself is distorted by application of a slight force, the optical characteristics of the optical element are fluctuated, and thus it can be problematic.
In contrast, recently, an optical element obtained by polymerization of a polymerizable liquid crystal material has been proposed (for example, Japanese Patent Application Laid-Open (JP-A) No.2001-100045, No.10-508882, or the like). According to the optical element, since the characteristics of the liquid crystal can be used as a film by solidification by polymerization, development to various applications is expected.
However, since maintenance of the hardness of the optical element, obtained by polymerization of a polymerizable liquid crystal material, itself at a high level has not been proposed conventionally, the problems of the above-mentioned accuracy as the optical device and the fluctuation of the optical characteristics of the optical element itself have not been solved.